Prior to Java SE 7 or earlier, you only had to take one exam to become certified (SCJP 5/SCJP 5). Now you need to complete two exams, OCA and OCP for Java SE 7.

The OCA Java SE 7 is a lot easier; it will build confidence before the harder exam (OCPJP 7). Prepare well for Java basics (OO concepts, declarations, etc), understand Java SE 7 changes, take OCAJP 7 exam and don't wait so song to take OCP exam.

EPractize Labs Training Labs for OCA Java SE 7(http://www.epractizelab.com/certification/sun/javase7oca.html) and OCP Java SE 7 are really good and on must have to clear this certification.

Study all API changes (JDBC, NIO2, etc) for OCP exam from Oracle's site. You may refer few chapters from K&B book.